Improvement in molds for casting steel



UNITED STATES PATENT OFFICE.

GEORGE COWING, OF CLEVELAND, OHIO.

lMPROVEMENT IN MOLDS FOR CASTING STEEL.

Specification forming part of Letters Patent No. 212,902, dated March 4,1879 application filed September 28, 1877.

To all whom it may concern:

Be it known that I, GEORGE COWING, of Cleveland, in the county ofCuyahoga and State of Ohio, have invented certain new and usefulImprovements in Molds for Casting Steel, &c. and I do hereby declare thefollowing to be a full, clear, and exact description of the invention,such as will enable others skilled in the art to which it pertains tomake and use it, reference being had to the accompanying drawings, whichform part of this specification.

My invention relates to molds and cores for casting steel, andespecially steel made by the open-hearth furnaces, which comes forth inits melted condition very much hotter than by any other method ofmelting at present known. It is on account of this intense heat of thismolten steel that has arisen the difficulties of its casting, becauseits contact against the walls of any molds of which I am aware as havingbeen employed for this purpose operates to fuse said walls in such amanner that a flux or scoria is formed, which coats the external surfaceof the casting, and is exceedin gly hard and diflicult and troublesometo remove.

Common sand, I am aware, has been experimented with as a substance fromwhich to form molds for the above-mentioned purpose; so, also, hasplumbago, charcoal, coke, and other carbons; also, potash and otheralkalies; but I have foun d that all these contain such matter, or areof such a nature, that the heat of molten steel from an open-hearthfurnace will form a flux and scoria, as above set forth.

The object of my invention is to form a mold from such a substance that,while suffieient for ordinary use as a molding material, will possesssuch refractory qualities as to successfully resist the tendency to fluxwhen brought in contact with the hottest molten steel.

For this purpose I construct my molds from pure, or nearly pure, silica,and this for the reason that I have found by extensive experiment andtest that when pure silica is employed a steel casting can always beproduced enl irely free from the flux or scoria referred to; and as puresilica is departed from, in that degree and proportion will the castingbe glazed or coated. When the silica is nearly pure,

such as can be secured by the use of rock-crystal, white sand, or whitepebble, a very good and satisfactory result is obtained.

As before remarked, I am aware that sand has been employed but it haseither been so far from being sufliciently pure silica, or else it hasbeen mixed or powdered with plumbago, charcoal, soot, coke, silicate ofpotash, or other alkali, or other substances, that the aforementionedflux is formed; and it is probably because a sufficiently pure silicahas never yet been employed that sand molds, or molds constructed frompowdered stone, 830., are today considered impracticable for use incasting steel from an open-hearth furnace.

I profess to be the first to have employed silica in its sufficient-lypure condition, and so long as the materials heretofore used (althoughcontaining a greater or less proportion of silica) have all containedsuch foreign matter as that open-hearth steel could not be successfullycast in molds constructed therefrom. Therefore I consider that mydiscovery and proofs that silica, when sufficiently pure, is actuallypracticable and operative and economic when employed as hereinspecified, constitute a new discovery and invention.

The state-of the art in this matter, so far as I am aware, demonstratesthat many have started in the right direction, and some have nearlyreached the point where my invention begins but all have stopped so farshort that open-hearth steel, if cast in any molds heretofore made,produces bad and unsatisfactory results; whereas I am easily enabled bymy invention and discovery to cast steel in an entirely acceptacle.manner and with the best results.

To prepare my molds I prefer to obtain my silica from rock-crystal,white pebble, or white sand. If white pebble or white sand be taken,they should first be pulverized and thoroughly purified and cleansedfrom foreign matter, such as metallic oxides, alkalies, 860. When aboutto be formed into molds, the silica is to be suitably mixed with anyappropriate binder, such as molasses, sounbeer, flour, starch, anyglutinous'substancefsilicate of aluminum, or

the like, care being taken that no substance be employed of thenature ofan alkali, or that contains any metallic oxide, or anything that wouldform a flux. A sufficient quantity of from a mass consisting of silicain its pure, or the selected binder is mixed with the pulvernearly pure,condition, and a binding or coheized silica to form a mass that can bemolded sive substance, substantially as and for the and be retained inthe desired shape. purpose specified.

Added to the advantages obtained by the In testimonywhereof I havesigned myname employment of this my invention is the abilto thisspecification in the presence of two sub-- ity to cast mild steeli. 0.,steel having a low scribing Witnesses. percentage of carbon-Which couldnot be done in molds consisting of or containing plumbago, GEORGEOOWlNG' charcoal, coke, or other form of carbon. I Witnesses:

What I claim is- F. TOUMEY, Molds or cores composed of or constructed W.E. DONNELLY.

